Vapor-pressure gauge



Dec. 9, 1930. P. M. GELATT I 1,784,052

VAPOR PRESSURE GAUGE Filed Jan. 26, 1929 vwentoz Patented Dec. 9, 1930UNITED STATES PATENT OFFICE HHLO M. em'rr,;or Mien BEACH, rrloiuna I i IVAPOR-PRESSURE GJAYUGE application filed January 26, i529, Serial No.835,238 I This invention relates to an improvement} part indicated 'inthe following description in vapor pressure gauges and particularlytbwand inpart rendered apparent therefrom in that type of gauge where'aBourdon tube is connection with the annexed drawings. employed. a Toenable othersskilled in the art so fully The invention has for itsgeneral objects to apprehend the underlying features herei to improvethe gauge in such a manner as to of that they may embody the same in themake the graduations on the scale or dial various ways contemplated bythis invention, plate more nearly uniform. A further ob drawingsdepicting a-preferred typical con- ]ect of the invention is tosimplifythe construction have been annexed as a part of this ,1 struction ofthis type of gauge by eliminatdisclosure and, in'such drawings, likecharing the'complicated mechanisms employed, acters of reference denotecorresponding entailing, as they do, seriousdefects, wherepartsthroughout all the views, of which by a more accurate instrument isproduced. Figure 1 is an elevation with part of the The ordinary type ofgauge consists of a dial broken away to show the position of 5 casing inwhich is mounted the Bourdon tube the parts at the22 temperatureindication. so

having one fixed end and one free end. In ,Fig. 2 is a correspondingView of the parts this .improved type of gauge the free end at the 50indicatiomthe dial being entirely of the tube is connected to thetail-piece by removed. Fig. 3 is a corresponding view, a gear segmentwhich actuates the pointer. when maximum pressur'e is exerted. Fig. 4

f Heretofore means have been provided for isamodification, while Fig.5isadetail view varying the ratio on the tail-piece as the of the dial.

Bourdon tube deflects, but all of these prior The Bourdon tube is marked1 and is constructions, so far as I am informed, have .shown secured atitsfixed end 2 to the-casting one or more effective points at which this3 and at its free end 4 has a sector shaped transition occurs but thereis nogradual member 5 pivotally mounted thereon. The

transition from one ratio to another, hence periphery of this member 5is formed with it has been impossible to employ a dial with gear teethwhich mesh with the gear teeth substantially uniform spacing throughoutformed on the tail-piece 6, which is part of the range, ofmovement ofthe pointer over the crank arm 7 which has a sector shaped the dial. Amain object of this invention upper member 8 formed with gear teeth isto arrange the parts of a vapor pressure engaging with. thepinion 9 towhich the gauge so that there will be a gradual transipointer 10 isconnected. This crank arm 7 tion due to a rapidly accelerating action ofis pivotally mounted at 11. the coupling devices that connect the Bour-The tail-piece 6 is preferably of skeleton 3 don tube with the pointer,it being underform and carries a pivot 12 at one end and on stood thatwith some kinds of vapor the inthis. pivot is mounted a link 13 which ispivcrease of pressure between zero temperature ota-lly connected at itsother end to the free and 10 centigrade is 15 pounds per square end 4 ofthe Bourdon tube. In this manner inchwhile between 90,and 100 theincrease the sectormember 5 is maintained in mesh is as much as 70pounds persquare inch. with ,thetail-piec1e 6 during the movement,Consequently, there should be an accelerating of the .Bourdon tube. Asatisfactory result action between certain temperatures of'the is alsovobtained by substituting a coiled vapor in order to produce a uniformscale .spring for link '13. In the modification marking for the high andlow temperatures. shown inFig. ithe spring '14 is substituted 4 Otherobjects and advantages will bel in for the link 13, one end of this coilspring the dial graduations is made possible by the rolling engagementof the sector 5 with the tail-piece 6 causing a gradually acceleratingmovement of the pointer inversely proportionate to the movement of theend of the Bourdon tube as the latter deflects under pressure, thetheory being that as the tube deflects under pressure, the gear attachedto the end of the tuberolls. outward on, the toothed tail-piece 6, andby so doing decreases the' ratio of movement ofthe tube and pointer. Aswill be readily seen by com--' paring Figs. 1 and 3 the point of contact"of gears on sector 5'and sector 6, as it rolls outwardly, moves awayfrom the center 11 on which the sector 7 oscillates, hence itis apparentthat the leverages are changed, and the amount of movement transmittedby an increment of deflection of the tube to the pinion 9 and itspointer will be much reduced when the point of contact of the gearsreaches the position shown in Fig. 3 as compared with the amount ofmovement transmitted bythe same increment of defiectionin the positionshown in Fig. 1. The pointer travel maybe made to function moreuniformally by substituting a rackand elliptical gear combination forthe gear se ments 6 and 5 shown in the drawings, and maintaining the twounits in contact by means of a tension spring 14 as shown in Fig. 4.

Without further analysis, the foregoing will so fully reveal the gist ofthisinvention that others can, by applyingcurrent knowledge, readilyadapt it for various utilizations by retaining one or more of thefeatures that, from the standpoint of the prior art, fairly constituteessential characteristics of either the generic or-specific aspects oi?this invention and, therefore, suchadaptations should be, and areintended to be, comprehended within the meaning and range of equivalencyoi the following claims.

Having thus revealed this invention, I claim as new and desire to securethe following combinations and elements, or equiva'- len'ts thereof, byLetters Patent of United States 1. In an instrument of the characterspecified, characterized as having a Bourdon tube and rotatable'pointercontrolled by the vapor pressure of said tube, thecombination of anintermediate member with gear teeth thereon, pivotally mounted on thefree end of said tube; an additional pivoted gear in mesh with the gearteeth of said member; and connecting means between said additional gearand said pointer, the contacting point of the intermeshing gear rollingoutwardly from the pivot of said additional gear whenever said tube isdeflected outwardly, thereby automatically changing the leverage of themembers intermediate said tube and pointer.

2. In an instrument of the character specified the combination of anexpansible member subject to vapor pressure with a rotatable pointercontrolled by said vapor pressure, inter-meshing gears, one beingmounted'on and carried by the free end of said eXpansible member and theother connected with said pointer, and means for holding said gears inmesh, both gears being pivotally mounted and movable relatively to saidtube upon the deflection of said tube whereby upon its deflection thecontacting point of said gears will move automatically to difle'rentposi- "tions.

3. In an instrument of the character specified the combination of anexpansible memher subject to vapor pressure with a rotatable pointercontrolled by said vapor pressure, intermeshing gears, one beingpivotally mounted on the free end of said expansible member and theother pivotally connected with said pointer, and a connecting barpivotally connected to said gears for holding said gears in mesh andpermitting the point of contact of said gears to move outwardly from thepivot of said other gear during the outward movement of the 'free end ofsaid expansible member.

4. A pressure gauge combining a Bourdon tube; a rotatable pointer; alever :E'ulcrumed intermediate its ends, one end of said lever having agear connection with said pointer for rotating the latter and theother-end of said lever having an arcuate portion; a member pivotallymounted upon the free end of said Bourdon tube and having an arcuateportion in rolling engagement with the arcuate portion of said lever;and means to maintain said arcuate portions in rolling contact duringdeflection of said Bourdon tube.

5. A pressure gauge combininga Bourdon tube; a rotatable pointer; alover of the first order formed with first and second gear segnients atopposite sides of its fulcrum; a pinion connected with said pointer andengaging said first gear segment; a member pivoted upon the free endof's'aid Bourdon tube and" having a'seginental gear portion engaging thesecond gear segment; and a link connecting the. free end of said Bourdontube with said lever and serving to maintain said'second gear segmentand said segmental portion in rolling contact during deflection of saidBourdon tube.

6. A pressure gauge combininga support; pointer pivoted thereon; aBourdontube having one end fixed to said support; a lever fulcrumedintermediate its ends to said support and having, at its opposite ends,first and second gear segments; a pinion connected with said pointer andengaging said first gear segment; a member pivoted upon the free end ofsaid Bourdon tube and having a segmental gear portion engaging saidsecond gear segment; and a spring tending to rotate said pinion andthereby maintain said second gear segment and said segmental portion incontact during deflection of said Bourdon tube.

In Witness whereof, I have hereunto subscribed my name.

PHILO M. GELATT.

